package org.bouncycastle.jce.provider;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.math.BigInteger;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.RSAPublicKeySpec;

import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DERNull;
import org.bouncycastle.asn1.DEROutputStream;
import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.asn1.x509.RSAPublicKeyStructure;
import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.crypto.params.RSAKeyParameters;

public class JCERSAPublicKey implements RSAPublicKey {
    private BigInteger modulus;
    private BigInteger publicExponent;

    JCERSAPublicKey(RSAKeyParameters key) {
        this.modulus = key.getModulus();
        this.publicExponent = key.getExponent();
    }

    JCERSAPublicKey(RSAPublicKeySpec spec) {
        this.modulus = spec.getModulus();
        this.publicExponent = spec.getPublicExponent();
    }

    JCERSAPublicKey(RSAPublicKey key) {
        this.modulus = key.getModulus();
        this.publicExponent = key.getPublicExponent();
    }

    JCERSAPublicKey(SubjectPublicKeyInfo info) {
        try {
            RSAPublicKeyStructure pubKey = new RSAPublicKeyStructure((ASN1Sequence) info.getPublicKey());

            this.modulus = pubKey.getModulus();
            this.publicExponent = pubKey.getPublicExponent();
        } catch (IOException e) {
            throw new IllegalArgumentException("invalid info structure in RSA public key");
        }
    }

    /**
     * return the modulus.
     * 
     * @return the modulus.
     */
    public BigInteger getModulus() {
        return modulus;
    }

    /**
     * return the public exponent.
     * 
     * @return the public exponent.
     */
    public BigInteger getPublicExponent() {
        return publicExponent;
    }

    public String getAlgorithm() {
        return "RSA";
    }

    public String getFormat() {
        return "X.509";
    }

    public byte[] getEncoded() {
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();
        DEROutputStream dOut = new DEROutputStream(bOut);
        SubjectPublicKeyInfo info =
                new SubjectPublicKeyInfo(new AlgorithmIdentifier(PKCSObjectIdentifiers.rsaEncryption, new DERNull()), new RSAPublicKeyStructure(
                        getModulus(), getPublicExponent()).getDERObject());

        try {
            dOut.writeObject(info);
            dOut.close();
        } catch (IOException e) {
            throw new RuntimeException("Error encoding RSA public key");
        }

        return bOut.toByteArray();

    }

    public boolean equals(Object o) {
        if (!(o instanceof RSAPublicKey)) {
            return false;
        }

        if (o == this) {
            return true;
        }

        RSAPublicKey key = (RSAPublicKey) o;

        return getModulus().equals(key.getModulus()) && getPublicExponent().equals(key.getPublicExponent());
    }

    public String toString() {
        StringBuffer buf = new StringBuffer();
        String nl = System.getProperty("line.separator");

        buf.append("RSA Public Key" + nl);
        buf.append("            modulus: " + this.getModulus().toString(16) + nl);
        buf.append("    public exponent: " + this.getPublicExponent().toString(16) + nl);

        return buf.toString();
    }
}
